Riluzole (Rilutek) is currently the only drug licensed for treating ALS in the UK. The licensed indication of riluzole is to extend life or the time to mechanical ventilation for individuals with ALS. The Summary of Product Characteristics (SPC) recommends that riluzole should not be used in any other form of motor neurone disease (MND). The SPC also suggests that treatment should only be initiated by specialist physicians with experience in the management of MND.
It is hypothesised that excessive stimulation of glutamate receptors on neurones may cause or play an important role in the destruction of motor neurones in MND. Glutamate is a neurotransmitter that tends to excite motor neurone cells. In vitro, riluzole inhibits the release of glutamate, decreases firing of motor neurones induced by glutamate receptor agonists and thus protects cells from glutamate-mediated damage.
The main caution for use of riluzole is history of abnormal hepatic function. Regular blood testing (every month for 3 months, then every 3 months for a further 9 months and annually thereafter) is recommended to monitor hepatic function. Side effects include nausea, vomiting, weakness, tachycardia, somnolence, headache, dizziness, vertigo, pain, parasthesia and alterations in liver function tests. Side effects of dizziness or vertigo may affect the performance of skilled tasks such as driving. Riluzole is contraindicated in the presence of hepatic and/or renal impairment and during pregnancy and breastfeeding.
The license dosage of riluzole is 100 mg per day (50 mg twice per day). The NHS list price (excluding VAT) of riluzole is £286 per treatment course, which amounts to an annual cost of £3,718. An additional cost, incurred for monitoring liver enzymes, has been estimated to be a maximum of £24 per year, giving a total annual cost of treatment with riluzole of £3,742.